My guess...
Not this:
子供の頃から憧れ続けていた {存在の一員} になれる気分。。。そう言えば伝わるかな?
This:
子供の頃から {憧れ続けていた存在} の一員になれる気分。。。そう言えば伝わるかな?
Is there any further context to go with this?
Or maybe the guy just had such an underdeveloped sense of self that he felt below the plane of existence somehow and just longed to feel he was even one of the insignificant unwashed masses?
Where did you get this?